Heart failure due to damaged cardiac tissue is a significant health care issue. It has been proposed to treat the damaged tissue directly with a therapeutic agent designed to help regenerate the damaged tissue. An example of a therapeutic agent proposed for this use is stem cells. The stem cells would be delivered in the form of a gel to the site of the damaged tissue. The gels, however, have relatively high viscosities. Therefore, administering the gel through a conventional syringe would subject the stem cells to relatively high pressure, potentially damaging the cells and compromising their therapeutic efficacy.